Electric circuit breaker



Feb. 16, 1954 E 2,669,626

ELECTRIC CIRCUIT BREAKER Filed March 31, 1951 IhVentor: Raymond NHRowe,

His Attorney- Patented Feb. 16, 1954 UNITED STATES PATENT OFFICE.

by mesneassignments, to

General Electric Company, a corporation of New York Application March 31, 1951, Serial No. 218,647

12 Claims. 1

The invention relates to breakers which will open a circuit automatically not only upon a small prolonged overload but upon a sudden heavy overload and which may be actuated manually.

The main object is to provide tripping mechanism, for an automatic circuit breaker, which is not easily aifected by physical shock or vibration.

Another object is to secure a quick break in case of an overload.

Another object is to provide a tripping mechanism which is simple in construction and economical to manufacture.

Fig. 1 is a side view of an insulating housing with the improved mechanism in the closed circuit position.

Fig. 2 is a view of a part of the housing with the latching mechanism in the tripped position.

The housing I may be of any suitable form preferably of molded insulating material with recesses and abutments located to accommodate the mechanism.

The circuit terminals 8 and 9 may be of any suitable form and preferably are located in opposite ends of the housing. Stationary contact I is connected to terminal 8 by conducting strip Ill and the movable contact H" is mounted and actuated in any well known manner, for instance, as shown in the Getchell Patent No. 2,455,753.

The actuating lever I2 is pivoted in the housing at I3. Its upper end is movable back and forth in the slot [4 in the top of the housing.

The cradle I5 is pivoted at I6 in the housing and has a tripping arm IT.

The movable switch arm H is pivoted at I 8 in the cradle l5.

. A throwing spring 19 is connected at its upper end to the actuating lever l2 and at the lower end to the switch arm I I.

To open the circuit manually, the lever I2 is moved to the right '(Fig. l) and when the direction of pull of the spring [9 passes the line of center, the spring 19 will suddenly throw the switch arm I l to the open circuit position. It will be understood that suitable arc minimizing means (not shown) may be employed.

The lower end of the bimetal arm 20 is'mounted on a metallic support 2| to which the switch arm I l is connected by the flexible cord 22. The

upper end of the bimetal arm 20 is connected to terminal 9 by the flexible cord 23 and conducting strip 23.

' The latch lever or member 25 is pivoted at 26 to'the housing with'its lower end 21 normally 'interposed in the path'of movement of thetripping 2 arm H: which is biased upward to an open circuit position by the spring [9.

The upper end 28 of the latching member carries a. bimetal buckling member or disc 29 which is secured to the member 25 by a thermally conductive screw 30. The upper and lower edges of the curved member 29 are seated against the abutments 3i and 32, respectively.

A compression spring 33 interposed between the stationary abutment 34 and the arm 25 urges the arm toward latching position.

An adjustable stud 35 is mounted in the upper end of the bimetal strip 20.

In order to adjust or calibrate the breaker, I provide an opening 36 in the housing in line with the center contact stud 35.

In normal use the parts are in the position of Fig. 1. In case of a slight, but prolonged overload in the circut, the bimetal member becomes heated and the upper end bends or warps to the left. The stud 35 engages the head of the screw 30 and conducts heat from the bimetal 2'0 suflicient to distort the disc member 29. When the member 29 gets hot it will suddenly buckle .from the position of Fig. l to that of Fig. 2. This sudden action snaps the latching arm from the position of Fig. 1 to the reverse curvature position of Fig. 2 and releases the trip arm I] whereupon the spring l9 throws the arm I! to the position of Fig. 2-a quick break, leaving the actuating lever i2 in the mid-position ready for resetting.

In case of a sudden heavy overload in the circuit, the bimetal member 20 warps as in the case of a gradual prolonged smaller overload but much more rapidly. The stud 35 engages the head of screw and on continued further travel will force the latching lever 25 to turn on its pivot directly to the released position whether the disc 29 has snapped over or not.

When the disc 29 cools off it will resume the position of Fig. 1 and the circuit may then be closed.

its preferred form, the invention contemplates a circuit breaker having a member movable to cause tripping and two bimetal elements, one of which is energized by current passing the-rethrough and the other adapted to be heated by heat generated in the first element so arranged that the warping of either bimetal element causes movement of the movable member to cause tripping.

I claim:

1. In a circuit'breaker, a tripping member, a movably mounted latching member for said tripping member, a bimetal buckling member mounted on said latching member, and an overload actuated member having means for transmitting heat to said buckling member, both said buckling member and said overload-actuated member tending to retract said latching member from said trip- Ding member in response to a rise in temperature.

2. In a circuit breaker, a tripping member, a latching member normally restraining said tripping member, a movably mounted snap action bimetal device operating in response to a rise in temperature to retract said latching member from said tripping member, means for moving said bimetal device including a bimetal overload actuated member tending to release said latching member from said tripping member in response to a rise in temperature and means for conducting heat to said bimetal device from said bimetal member.

3. In a circuit breaker having a tripping member, a pivoted latching lever normally preventing movement of the tripping member, a bimetal arm having a movable end, a bimetal buckling member carried by said latching lever, and means carried by said bimetal arm for heating said buckling member and retracting said latching lever from said tripping member.

4. In a circuit breaker having a tripping member, a pivoted latching lever normally preventing movement of the tripping member, a bimetal arm having on end movable, a buckling member carried by said latching lever, and means carried by said bimetal arm coacting with said buckling member to retract said latching lever from said tripping member in case of an overload.

5. In a circuit breaker having manually actuated mechanism for opening and closing a circuit, a tripping member connected therewith, a pivoted latching lever normally preventing movement or the tripping member, an overload-actuated member having a movable end, a buckling member carried by said latching lever, and means carried by said overload-actuated member coacting with said buckling member to transfer heat thereto, both said buckling member and said overloadactuated member tending to retract said latching lever from said tripping member in response to overload current through said breaker.

6. In a circuit breaker, a movable tripping member, a latch for said tripping member, a first bimetal member forming a circuit element and adapted to be warped by current passing therethrough, a second bimetal element positioned close to said first bimetal member and adapted to be heated from and engaged by the first mentioned bimetal element and an operating'connection between said second bimetal element and said latch so arranged that Warping of either ele ment in response to an increase in temperature causes release of said tripping member.

7. In a circuit breaker, a movable contact, a tripping member controlling the movement of said movable contact, a latching member controlling the movement of said tripping member, a bimetal element for moving said latching member to disengage said tripping member in response to an increase in temperature, and a second bimetal element in circuit with said movable contact controlling the movement of said first-named. bimetal element, the relative arrangement of said bimetal elements being such that warping of either bimetal element in response to'a rise in temperature moves said latching member and effects movement of the tripping member.

8. A circuitbreaker comprising contact means for opening and closing an electric circuit, manually actuated means for operating said contact means, a tripping member biased to an open circuit position, a latch for holding said tripping member in a closed circuit position, a movably mounted snap operating first bimetal member having a first portion relatively movable with respect to a second portion in response to a change in temperature, an operating connection between said first portion and said latch for moving said latch to release said tripping member, a second bimetal member connected in an electric circuit with said contact means so as to be heated by the current in said contact means, said second bimetal member having a portion moving in response to an overload current for engaging said first bimetal member to conduct heat to said first bimetal member for snap operation thereof, and for moving in response to a higher overload current said first bimetal member and said latch to release said tripping member before said first bimetal member has been heated sufficiently to operate.

9. A circuit breaker comprising contact means for opening and closing an electric circuit, manually actuated means for operating said contact means, a tripping member biased to an open circuit position, a pivotally mounted latch member for holding said tripping member in a closed circuit position, a snap operating first bimetal member having a first portion relatively movable with respect to a second portion in response to a change in temperature, means securing saidfirst portion to said latch member so that said bimetal member is mounted on said latch member, abutment means engaged by said second portion so that movement of said first portion moves said latch member to release said tripping member, a second bimetal member connected in an electric circuit with said contact means so as to be heated by the current in said contact means, said second bimetal member having a portion moving in response to an overload current for engaging said first bimetal member to conduct heat to said first bimetal member for snap operation thereof, and for moving in response to a higher overload current said first bimetal member and said latch member to release said tripping member before said first bimetal member has been heated sufiiciently to operate.

10. A circuit breaker comprising contact means for opening and closing an electric circuit, manually actuating means for operating said contact means, a tripping member biased to an open circuit position, a latch member pivotally mounted intermediate its ends and having one end normally engaging said tripping member to hold it in a closed circuit position, a snap operating bimetal disk having its center secured to the other end of said latch member so that said bimetal disk is mounted on said latch member, stationary abutments against which the edges of the said disk normally rest, said disk being arranged to snap to a reversed curvature position in response to an increase in temperature thereby tomove said latch member to release said tripping member, a bimetal strip electrically connected in circuit with said contact means so as to be heated by the current in said contact means and having a portion moving in response to an overload current into engagement with the center of said disk for the conduction of heat to said disk, and for moving in response to a higher overload current said disk and said latch member to release said tripping member before said disk has been heated sufliciently to operate.

11. A circuit breaker comprising contact means for opening and closing an electric circuit, mechanism for operating said contact means to open circuit position comprising a tripping member biased to an open circuit position, a latch for holding said tripping member in a closed circuit position and means for moving said latch in response to an overload current through said contact means to release said tripping member, said lastmentioned means comprising first and second bimetal members heated by current through said contact means and both tending upon an increase in temperature to move in a direction to efiect release of said tripping member.

12. A circuit breaker comprising contact means for opening and closing an electric circuit, mechanism for operating said contact means to open circuit position comprising a tripping member biased to an open circuit position, a latch for holding said tripping member in a closed circuit position and means for moving said latch in response to an overload current through said contact means to release said tripping member, said lastmentioned means comprising first and second bimetal members heated by current through said contact means and both tending upon an increase in temperature to move in a direction to effect release of said tripping member, one of said members moving gradually with temperature change and the other moving with a snap action in response to a predetermined temperature rise.

RAYMOND N. ROWE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,952,040 Frank et a1 Mar. 20, 1934 2,175,859 Tusing Oct. 10, 1939 2,406,325 Dorfman Aug. 27, 1946 2,455,753 Getchell Dec. 7, 1948 2,568,423 Walker et a1 Sept. 18, 1951 2,573,307 Casey Oct. 30, 1951 

